Coatings that provide low reflectivity or a high percent transmission over a broad wavelength range of light are desirable in many applications including semiconductor device manufacturing, solar cell manufacturing, glass manufacturing, and energy cell manufacturing. The transmission of light through a material causes the wavelength of the light to change, a process known as refraction, while the frequency remains unchanged thus changing the speed of light in the material. The refractive index of a material is a measure of the speed of light in that material which is generally expressed as a ratio of the speed of light in vacuum relative to that in the material. Low reflectivity coatings generally have an optimized refractive index (n) in between air (n=1) and glass (n˜1.5).
An antireflective (AR) coating is a type of low reflectivity coating applied to the surface of a transparent article to reduce reflectance of visible light from the article and enhance the transmission of such light into or through the article thus decreasing the refractive index.
Antireflective coatings are typically formed using a single layer of antireflective material. However, the theoretical limit for the improvement of optical transmittance for such coatings is ˜3.0%.